A coupled block copolymer composition with a combination of high viscosity at manufacturing, finishing and handling conditions, low viscosity at asphalt blending conditions and suitable viscosity stability is provided for use in asphalt compositions. The composition comprises: (i) a diblock copolymer, (ii) at least a linear triblock copolymer having a peak molecular weight that is 1.5 to 3.0 times the peak molecular weight of the diblock copolymer, and (iii) at least a multiarm coupled block copolymer having a peak molecular weight that is 1.5 to 9.0 times the peak molecular weight of the diblock copolymer, and mixtures thereof. The block copolymer composition is characterized as having a melt viscosity at 110° C. or less of greater than 2.0E7 Poise and a coupling efficiency after 24 hours at 180° C. is less than 25%.